I have a popup date selection calendar that works fine in older versions of Firefox, but the calendar's previous month and next month selections, do not work in Firefox 3. When you click on the forward or backward arrows, instead of showing the next month, the calendar just closes.

function Calendar_calc_month_year(p_Month, p_Year, incr) {
/*
Will return an 1-D array with 1st element being the calculated month
and second being the calculated year
after applying the month increment/decrement as specified by 'incr' parameter.
'incr' will normally have 1/-1 to navigate thru the months.
*/
var ret_arr = new Array();

/*
Get day for the 1st of the requested month/year..
Place as many blank cells before the 1st day of the month as necessary.
*/
vCode = vCode + "<tr>";
for (i=0; i<vFirstDay; i++) {
vCode = vCode + "<td class=\"we\">&nbsp;</td>";
}

The back-to-back calls to the Build() function confuse me so I could understand how the computer might become so also.

I'm also not sure that the <TD> tag has an onclick() function associated with it, but I haven't look this up yet.
If it does, then I'm not sure which action takes precedence, the <TH> or the <A>.

Again, I'm not sure this is the problem but it might be a start place in the code to investigate further.
Might try to eliminate one call to the 'Built()' function and then the other to see if it makes a difference.